The invention concerns a miniaturized directional antenna with a ceramic substrate having at least one resonant printed wiring structure, in particular for use in the high-frequency and microwave ranges. The invention also concerns a printed circuit board (PCB) for the surface mounting of electrical and/or electronic components (SMDxe2x80x94Surface-Mounted Devices) with an antenna of this kind.
Wireless radio networking is experiencing a steadily growing importance in modern telecommunications and, to an increasing extent, in entertainment electronics. Electromagnetic waves in the high-frequency and microwave ranges are used for the transmission of information. Examples of this are the mobile radio bands, which in Europe lie in the range between approximately 880 and 960 MHz (GSM 900) and between approximately 1710 and 1880 MHz (DCS 1800) and approximately 1850 and 1990 MHz (PCS 1900), the GPS navigation signals, which are emitted in a frequency band at approximately 1573 MHz, and the Bluetooth band in the frequency range between approximately 2400 MHz and 2500 MHz, which is used for the exchange of data between individual terminals.
The electronic components used for this purpose are subjected to ever higher requirements, in particular as regards their degree of miniaturization, their cost-effective mounting capability and their electrical efficiency. In the field of antennae, examples of the additional requirements imposed for their use in future mobile telephones are: internal locationing, multiband capability and reduced user irradiation and/or improved SAR (Specific Absorption Rate) values.
Conventional antennae for use in mobile telephones, such as external monopolar antennae or internal PIFA (Planar Inverted F Antenna) on dielectric substrates, fail to meet the above requirements, or meet them inadequately.
From JP-07 240 962 is known, for example, an antenna for mounting on a PCB which is equipped with ground plating and mounted in a mobile communications device in such a way that the ground plating lies between the user""s body and the radiation path of the emitted waves in order to achieve a screening effect by this means. In order to achieve adequate reception sensitivity, however, a separate rod antenna is needed.
It is an object of the invention, therefore, to produce an antenna of the type specified above that is equipped with an increased efficiency and an improved directional characteristic in a preferred direction.
Furthermore, an antenna of the type specified above is to be produced, in which impedance matching can be undertaken in a relatively simple manner.
An antenna of the type specified above, with which a relatively large bandwidth can be achieved, is also to be produced with the invention.
Finally, an antenna of the type specified above that is suitable for use in several of the above-specified frequency bands (multiband capability) is also to be produced.
Finally, a PCB with an antenna of the type specified above, with which the above-mentioned objectives can be especially well achieved, is also to be produced with the invention.
In one embodiment of the invention, a directional antenna with a ceramic substrate having at least one resonant printed wiring structure, is arranged on an electrically conductive motherboard with one end of the at least one printed wiring structure coupled to the motherboard.
A significant advantage of this solution consists in the fact that, with this antenna, a radiation characteristic directed largely only into a half-space can be achieved, end thereby the irradiation with electromagnetic waves of, for example, the user of a mobile telephone in which this antenna is incorporated can be significantly reduced.
The advantageous further features of the invention include:
through the suitable selection of the height of the substrate, a desired bandwidth of the antenna can be achieved;
a particularly high degree of miniaturization can be achieved;
impedance matching can be undertaken in a simple manner by changing the lead-in and thereby the capacitive coupling; and
the antenna according to the invention can be executed as part of a printed circuit board.